Combiner, head-up display device, and method for manufacturing combiner

Abstract

A combiner that displays display light from a light source as a display image by reflecting or diffracting the display light in a direction of an observer, the combiner comprising: a base material of a first thermoplastic resin; and an outer layer material of a second thermoplastic resin having a hardness higher than a hardness of the first thermoplastic resin and that covers part of a surface of the base material.

1 . A combiner that displays display light from a light source as a display image by reflecting or diffracting the display light in a direction of an observer, the combiner comprising:
 a base material of a first thermoplastic resin; and   an outer layer material of a second thermoplastic resin having a hardness higher than a hardness of the first thermoplastic resin and that covers part of a surface of the base material.   
     
     
         2 . The combiner according to  claim 1 , wherein a difference between a refractive index of the base material and a refractive index of the outer layer material is within 0.1. 
     
     
         3 . The combiner according to  claim 1 , wherein the base material comprises an optical surface that reflects or diffracts the display light, and the outer layer material covers at least the optical surface. 
     
     
         4 . The combiner according to  claim 1 , wherein
 the base material has an end face around an optical surface that reflects or diffracts the display light, and   the outer layer material covers the end face.   
     
     
         5 . The combiner according to  claim 1 , wherein
 the hardness of the base material is equal to or less than B in pencil hardness, and   the hardness of the outer layer material is equal to or greater than HB in pencil hardness.   
     
     
         6 . The combiner according to  claim 1 , wherein a difference between a linear expansion coefficient of the base material and a linear expansion coefficient of the outer layer material is within 10 −5  (/° C.). 
     
     
         7 . The combiner according to  claim 1 , wherein, a thickness of the outer layer material is equal to or greater than 0.01 (mm) and equal to or less than 0.3t (mm) when a thickness of the base material is set at t (mm). 
     
     
         8 . The combiner according to  claim 1 , wherein a glass-transition point temperature Tg of the outer layer material is equal to or lower than 156 (° C.). 
     
     
         9 . The combiner according to  claim 1 , wherein a function membrane is disposed on a surface of the outer layer material. 
     
     
         10 . The combiner according to  claim 9 , wherein the function membrane is formed with a dielectric body. 
     
     
         11 . The combiner according to  claim 9 , wherein the function membrane is a half mirror film with a reflectance of light having a wavelength between 420 (nm) and 680 (nm) that is equal to or higher than 20%. 
     
     
         12 . The combiner according to  claim 9 , wherein the function membrane is an antireflective film with a reflectance of light having a wavelength between 420 (nm) and 680 (nm) that is equal to or lower than 2%. 
     
     
         13 . A head-up display device comprising:
 the combiner according to  claim 1 , and   a drawing unit that emits the display light to the combiner.   
     
     
         14 . A method for manufacturing a combiner that displays display light from a light source as a display image by reflecting or diffracting the display light in a direction of an observer, the method comprising:
 forming a base material from a first thermoplastic resin; and   forming an outer layer material that covers part of a surface of the base material using a mold by bringing a second thermoplastic resin into contact with the first thermoplastic resin, wherein   the second thermoplastic resin has a hardness higher than a hardness of the first thermoplastic resin.   
     
     
         15 . The method for manufacturing the combiner according to  claim 14 , the method further comprising:
 forming a fine shape by forming the outer layer material at an end face of the base material using the mold.